Effect Of Ar Ion Bombardment Research Articles

Hydrogen effects on a-SiO 2: A photoemission study

Negative bias stress experiments on a-Si:H/a-SiO 2 Thin Film Transistors show that the instability is predominantly related to charge injection in the gate insulator. We propose that charge injection is occurring in a defected region of the gate insulator adjacent to a-Si:H, caused by the effect of activated hydrogen on a-SiO 2 surface during deposition. To investigate the hydrogen influence, we have studied low-energy (100 eV) hydrogen-ion and Ar-ion bombardment effects on a-SiO 2 using synchrotron radiation photoemission spectroscopies. Comparing the two kind of treatments, we show that hydrogen treatment produces predominantly Si-H defects, which are observed to induce gap states in a-SiO 2 .

Ion assisted deposition of thermally evaporated Ag and Al films

Optical, electrical, and microstructural effects of Ar-ion bombardment and Ar incorporation on thermally evaporated Ag and Al thin films are investigated. The results show that as the momentum supplied to the growing films by the bombarding ions per arriving metal atom increases, the refractive index at 632.8 nm increases and the extinction coefficient decreases, lattice spacing expands, grain size decreases, electrical resistivity increases, and trapped Ar increases slightly. In Ag films, stress reverses from tensile to compressive and in Al films compressive stress increases. In the Al films the change in optical constants can be explained by the variation in void volume. The reversal of stress from tensile to compressive in Ag films requires a threshold level of momentum. The increase in electrical resistivity is related to the decrease in grain size and increase in trapped Ar in both types of film. Many of these properties correlate well with the momentum transferred, suggesting that the momentum is an important physical parameter in describing the influence of ion beam on growing thin films and determining the characteristics of thin metal films prepared by ion assisted deposition.

Ion bombardment and titanium film growth on polyimide

The effects of Ar ion bombardment on the polyimide (PI) surface chemistry, Ti film growth, and the Ti/polyimide interface have been studied using x‐ray photoelectron spectroscopy (XPS). The Ti films were grown in an ultrahigh vacuum chamber onto spin coated polyimide substrates and then analyzed in situ by XPS. The substrates were, prior to Ti film deposition, exposed to ion doses of 3.8× and 30×1014 ions/cm2 using 2‐keV Ar ions. By monitoring the chemical shifts in the C 1s level arising from the polyimide molecular structure, a preferential bond breaking of imide carbonyl groups and formation of graphitelike carbons were observed as a consequence of the ion bombardment. As Ti was deposited a C 1s peak corresponding to Ti–C formation was observed for both as‐prepared and ion bombarded samples. The initial Ti film growth was studied by measuring the decrease in the C 1s level as a function of the amount of deposit. As expected for polymers the film growth is three dimensional in its character where islands of depositing atoms are formed in the initial stages. However, on ion bombarded PI substrates the number of nucleation sites is so large that the Ti film growth is comparable with a calculated layer‐by‐layer growth.

スパッタリング薄膜によるアルミニウムの液相拡散接合

Liquid phase diffusion welding of aluminium was studies. In this study, the surface of aluminium was cleaned by Ar ion beam bombardment and an alloyed film (Al-5wt.% Si-5wt.% Cu) was deposited on the bonding surface by sputtering. In this report, the effect of Ar ion bombardment on the oxide film of the bonding and weldability were investigated.The results indicated that: (1) Oxygen content on the bonding surface could be reduced by Ar ion bombardment, but the oxide film could not be removed perfectly. Wettability and weldability could be improved by Ar ion bombardment. (2) Upon heating, the alloyed film started to melt at 523°C. (3) Mechanical properties of diffusion welded joints equal to those of the base metal were obtained by the following condition: A welding temperature above 580°C, a pressure of 2 MPa and a welding time of lh.(4) Weld deformation was 1.68% with a welding temperature of 580°C and 3.28% with 610°C. Therefore, it was possible to make precise welding because weld deformation was less than that of conventional diffusion welding.

X-ray photoelectron spectroscopy studies of thin films of TiNx having different annealing histories

TiN thin films prepared by chemical vapor deposition (CVD) and annealed in different atmospheres were studied by means of x-ray photoelectron spectroscopy in conjunction with Ar ion bombardment. The films contained a high level of oxygen, and an intimate mixture of TiN and titanium oxide was postulated, based on the binding energy (BE) values of the Ti 2p core level photoelectrons. This was further supported by the independent effect of Ar ion bombardment on the two components and the constant nitrogen concentration throughout the film bulk. At this stage it seems unjustified to correlate differences in the Ti 2p spectra of the unsputtered samples with their annealing atmosphere histories, mainly because of the high oxygen content in all the films.

接合面合金化による拡散接合法の研究 ＩＩＩ スパッタ蒸着によるＩＮ７３８ＬＣ接合面への低融点合金層形成法の検討

Diffusion welding method using alloyed layer with sputtering after Ar ion bombarding on bonding surface of IN738LC has been studied.In this report, effect of Ar ion bombardment on oxide film of bonding surface, effect of sputtering condition on formation of alloyed layer and measurement of melting temperature were investigated.The results indicated that: oxide film on bonding surface can be removed by Ar ion bombardment, formation rate of alloyed layer is very fast in 3×10-3 Torr Ar and melting temperature of alloyed layer was 1080-1100°C.

XPS studies of the effect of argon ion bombardment on standard reference material 470: Glass K-411

The effect of Ar ion bombardment on Standard Reference Material 470: Glass K-411 with a composition of (Fe, Ca, Mg) 1.9Si 2O 6, was studied by means of XPS. Results show Fe to be most sensitive to ion induced damage, while no effect on the main photoelectron peaks of Ca, Si and O was observed. The oxygen, however, developed a small peak at lower BE (∼ 5.5 eV) of the main O 1 s peak on sputtering. This peak was correlated to an iron peak, Fe β, which developed also on sputtering, and the resultant oxide is believed to exist as a separate surface phase. O was found to be sputtered selectively with respect to Ca and Si which keep a constant atomic ratio. Mg could not be studied in the present composition.

Ar ion bombardment effects of NbN/Pb Josephson junctions with plasma oxidized barriers

Details of the relation between Ar ion bombardment effects on NbN surface and I-V characteristics of NbN/Pb junctions with plasma oxidized barriers have been studied. NbN base electrodes, which behave as a strong coupling superconductor (Tc>15 K, 2Δ/kTc=4.2–4.3), were prepared onto substrates at 300 °C by reactive dc magnetron sputtering. In the NbN/Pb junction fabrication, cathode self-bias voltage VCSB during Ar sputter cleaning strongly influences the subgap leakage current value, which increases with VCSB . The VCSB also influences normalized normal tunnel resistance ARNN. It is found, in reflection electron diffraction and x-ray photoelectron spectroscopy studies, that the Ar ion bombardment at VCSB> 200 V on a NbN surface produces an amorphous structure in the surface layer. It is also found that the thickness of amorphous layer increases with Ar ion energy. Based on the experimental results, low subgap leakage current junctions, where Vm exceeds 100 mV at 4.2 K, were fabricated under low energy plasma oxidation conditions, where Vm is the product of Josephson critical current and subgap resistance. Sputter cleaning and plasma oxidation conditions for obtaining high quality junctions are also discussed.

Microstructure and properties of rf-sputtered amorphous hydrogenated silicon films

The effect of both total gas pressure (Ar+H2) and partial pressure of H2 during the rf-sputtering of amorphous hydrogenated silicon films was investigated. It is shown that decreasing the total gas pressure (PT) leads to a number of consistent and desirable film characteristics including no post-deposition oxidation, essentially zero etch rate, no resolvable microstructure, predominant monohydride bonding, and low optical band gap. These lowest PT films contain ∼17 at. % H and 4 at. % Ar, have reasonable deposition rates (60–70 Å/min) and are in a high state of compressive stress. The relations between the deposition variables and the more fundamental surface reaction processes are discussed. Specifically, we demonstrate that Ar ion bombardment effects, due to high negative substrate self-biases, are dominant at low PT.

Niobium silicide formation induced by Ar-ion bombardment

The effect of Ar-ion bombardment on evaporated–Nb-on-Si systems has been investigated with He backscattering and x-ray-diffraction measurements. High-dose bombardment with energetic Ar ions was found to induce intermixing between Nb and Si in the form of NbSi2. This effect has strong dependence on temperature during bombardment, although it cannot be explained as enhanced diffusion due to radiation damage or ion-beam heating.